The present invention relates to a novel and useful railroad switching apparatus, using an over-the-tie structure.
Railway switches employ moveable rails or points which are associated with moveable indicator or detector rods. Such indicator rods are normally mechanically or electronically monitored in order to determine whether or not the points have properly traveled from one position to another in the switching operation. In addition, lock rods are employed to hold the points securely in place after they have switched positions. Further, a throw rod is also employed to apply forces which effect the mechanical switching.
In the past, indicator rods have been normally found adjacent to or between ties, either in a crib or on the railroad bed. Such cribs are normally located at or below the grade of the railway gravel bed. The absence of ballast around indicator rods found in such cribs provides access to the same, but the absence of ballast also causes lack of support and stability of the rails passing over the cribs. In addition, such crib structures prevent tamping of the ballast or gravel. Moreover, fouling of cribs or channels holding indicator or rods occurs over time.
In addition, thermal expansion and contraction of rails and movement of associated points tends to undermind the adjacent ties and requires special technique to tamp ballast in the near vicinity of such ties. Also, the thermal expansion and contraction of the rails and points often causes misalignment of the indicator rods and the detectors and may cause malfunction of controls used to determine the proper switching of the points.
Reference is made to U.S. Pat. No. 6,158,698 which shows a hollow tie switch assembly that employs U-shaped channels to confine indicator rods between connections to the points and the particular control and detection mechanism. However, such channels lie below grade and suffer many of the problems in the prior art in that the ballast used on track beds tends to foul and damage the indicator rods and the channels themselves.
A railroad track switching apparatus which overcomes the problems of the prior art and provides an unobstructed and accurate movement of the indicator rods connected to the rail points would be a notable advance in the railroad industry.